General purpose engines have been in use for well over a century. Early types included steam driven, hydro powered, and internal combustion powered engines that accomplished a myriad of tasks. Tasks such as milling, irrigation, and factory machine power were the first uses. The advent of the railroad saw steam powered engines that were powerful enough to pull very heavy loads for a relatively small physical size.
But near the end of the nineteenth century the motor vehicle made its debut, enabled by comparatively very small physical engines that produced a sufficient amount of power to drive a vehicle with passengers. While steam engines and internal combustion engines competed in the early going, the internal combustion engine became the standard based upon ease of construction, safety, and a source of cheap fuel.
Over the next century the design of the internal combustion engine was greatly improved. Diesel powered engines having high efficiency for a small size appeared. Turbo charged engines also were developed to gain power while keeping the engine size down. Other forms of fossil fuel engines have been developed that use propane, alcohol, ethanol, or a mixture of these. As long as there exists a cheap form of fuel, the internal combustion engine is the power plant of choice because it exhibits a wide range of power over its operating RPM range.
But the internal combustion engine has a number of serious drawbacks. First, the byproduct of the combustion is hydrocarbon and nitrogen oxide pollutants. These pollutants have proven to be harmful to human life and to the environment. No matter which fuel is selected, the byproduct of the combustion will be hydrocarbon effluents. Numerous techniques have been developed to reduce the level of pollutants such as MTBE (methyl tertiary-butyl ether), but due to the incomplete nature of the explosions in an internal combustion engine, coupled to the inefficient extraction of power, exhaust gases always contain pollutants.
A second drawback to internal combustion engines is inefficiency. The internal combustion engine is inefficient because the power extracted to drive a load is the result of the transformation of the energy in the combustion reaction to mechanical elements such as a pistons, crankshaft and connecting rods. For each additional piston an additional friction load is placed on the engine requiring larger cooling systems. The inefficiency is exacerbated by the heat lost in the cooling system. This dissipated heat is a direct energy loss that cannot be recaptured. A further inefficiency exists in modern internal combustion engines equipped with catalytic converters. Due to the less-than-optimum air/fuel mixture in the cylinders, unexpended fuel enters the exhaust gas flow. To reduce pollutants a catalytic converter is used to burn off this excess fuel. The energy is lost as heat. As will be described below, the method of the present invention uses the force of the combustion reaction directly to extract power to drive a load.
A third drawback of the internal combustion engine is that it is complex. Extremely tight tolerances are required in the design and manufacture of an internal combustion engine. With the advent of more restrictive pollution standards, the addition of closed loop pollution controls and computer control centers has only exacerbated the complexity and reduced efficiency. As will be seen from the detailed discussion below, the method of the present invention greatly simplifies the design of the general purpose engine, making it more efficient and thus more economical.
Also developed during the twentieth century were other types of engines including rocket engines of both solid and liquid fuel types, jet engines and electric motors, including the modern fuel cell technologies. Rocket and jet engines, while suitable for certain tasks such as military aircraft or space exploration, find little practical use in the general purpose engine area. Thus while both types of engines are simple in design, both suffer from inefficiency and impracticality when looking at general purpose engine applications.
Also disadvantageous is the hazardous nature of both rocket and jet engines. Although simple in design, due to the high operating pressures and extreme volatility of the fuels required, these types of engines are not suitable for the general purpose tasks mentioned above. Finally, both rocket and jet engines are expensive to operate due to the constant maintenance required to guarantee that the tight tolerances and critical components remain within specifications.
Electric motors for providing power are advantageous for fixed installations where a ready source of electricity is available. However, for use in those applications where electricity is not available, or where the power plant must be portable, as in a vehicle, electric motors and associated technologies have not yet matured to the point where they are economical. Fuel cell technology provides a promise for simple, efficient and clean power for electric motors in the future, but is not ready today.
What is required is an engine design that has the operational simplicity of a jet engine but the low cost, safety and maintenance ease of an internal combustion engine. The engine disclosed by the present invention provides such a design.